Preparation And Properties Of TiO₂ Coating Flouride Co-doped By Tm³⁺, Yb³⁺ Composite Nano Photosensitive Material

With the improvement of people’s living standards, people’s health and hygiene requirements are high, especially for water or air purification, antibacterial material aspects. As a leader in photo-catalyst, nano-TiO₂ with a high oxidation activity, chemical stability, non-toxic side effects on the human body, and no secondary pollution to the environment, low cost, etc., are widely used in the purification of biodegradable materials and inorganic antibacterial material field. But its band gap reaches 3.2ev, only absorbs and utilizes less than 387.5nm Ultraviolet Rays（UV）, which limits its utilization of light and the scope of application. This article utilized the method of photosensitive modification for nano- TiO₂ by up-conversion luminescence material, thereby expanding its optical response range and light utilization.The method used in this experiment was "a two-step hydrothermal method". That is the basis of the hydrothermal synthesis of nano-TiO₂, through adjusting the pH value of the hydrothermal system（under acidic） and adding different amounts of the up-conversion of calcium fluoride nano powder to improve the encapsulation layer thickness of nano- TiO₂ photocatalyst and its near- infrared photocatalytic capacity, near- infrared antibacterial properties. This method has the advantages of the required simple equipment, easy operation, high product purity and low calcination temperature.In the hydrothermal preparation of up-conversion fluorescent material of Tm³⁺、Yb³⁺ co-doped calcium fluoride, when the light emitting ion Tm³⁺ molar concentration was 0.4%, the sensitizer ion Yb³⁺ molar concentration was 20%, hydrothermal conditions were 180°C and 12 h, calcined temperature was 500°C, nano phosphor obtained the excellence of crystallinity, single particle dispersion, particle size uniformity, up-conversion luminescence efficiency, whose phase was（CaY） F2 and its average size was 55.5nm. It could be stably excited by a 980 nm pump light and converted to 360 nm UV.On the hydrothermal synthesis process of composite nano-clusters powder having core-shell structure with Tm³⁺、Yb³⁺ co-doped calcium fluoride wrapped by TiO₂, When TiO₂ :（CaY） F2 molar ratio was 4: 1, the resulting composite powder had an excellent near-infrared light catalytic degradation ability. And when pH was 0.2, hydrothermal conditions were 120°C and 8h, calcined temperature was 400°C,（CaY） F2 noncrystalline was wrapped 5.6nm layer of the anatase phase, which had been the nano multifunctional composite powder. At the near- infrared light, its degradation rate toward methyl orange solution was to 93.33% and its minimum inhibitory concentration was to 250 ppm, having certain antibacterial capability.